A signal adjusting device for adjusting a signal when the signal is transmitted from a transmitting unit to a receiving unit via a signal line is known. In the signal adjusting device, a termination resistor unit in which a signal line is subjected to termination processing is connected to the signal line in order that an adverse effect such as variation of the amplitude of a signal, generation of a stepped signal waveform, distortion, turbulence, or the like of a signal due to reflection, or the like of the signal is not imposed on the signal.
For such a signal adjusting processing device, a signal adjusting device in which a termination resistor unit having a uniquely determined optimum resistance value is provided with respect to a transmitting unit which comprises in advance an internal processing circuit, an output buffer for outputting an processing result of the internal processing circuit to a signal line, and a code check bit insertion circuit provided therebetween, and in which the uniquely determined resistance value of the termination resistor unit is changed in accordance with the variation of a margin for a mask that an eye pattern opening has been proposed (for example, Japanese Unexamined Patent Publication No. JP-A-2009-159256).
In some cases, a position detector which is used for a motor control device and which detects the position of a motor can be connected to a receiving unit via a signal line, and a detection signal is transmitted from the connected position detector to the receiving unit via the signal line. In cases in which a signal line is subjected to a termination processing by using a termination resistor unit, an optimum resistance value of the termination resistor unit in order that adverse effect is not imposed on a detection signal differs depending on the type of the position detector to which the receiving unit is connected. For example, the optimum resistance value of a termination resistor unit in cases in which a position detector manufactured by a specified manufacturer is connected to a receiving unit differs from the optimum resistance value of a termination resistor unit in cases in which a position detector manufactured by another manufacturer is connected to a receiving unit.
Accordingly, it is difficult to set an optimum resistance value of a termination resistor unit with respect to a position detector connected to a receiving unit. Further, in order to set an optimum resistance value of the termination resistor unit for the position detector to which the receiving unit is connected, another resistor may be added to the termination resistor unit to omit some resistors included in the termination resistor unit, or a resistor included in the termination resistor unit may be changed to another resistor.
An object of the invention is to provide a signal adjusting device in which a resistance value of a termination resistor unit can be set to an appropriate value depending on the type of a position detector to which a receiving unit is connected without adding, omitting, or changing a resistor.